Nine new species and one new subspecies of Hoya (Apocynaceae: Asclepiadoideae) from Borneo

Abstract

. In the present paper we publish nine new species and one new subspecies from Borneo, Hoya ariffinii Rodda & S.Rahayu, H. boycei Rodda & S.Rahayu, H. curtisii King & Gamble subsp. collariata S.Rahayu & Rodda, H. dulitensis Rodda & S.Rahayu, H. kaikoeana S.Rahayu & Rodda, H. kapuasensis S.Rahayu & Rodda, H. kerangasensis Rodda & S.Rahayu, H. peltata Rodda & S.Rahayu, H. polypus S.Rahayu & Rodda and H. sangguensis S.Rahayu & Rodda. Five species are endemic to Kalimantan, two to Brunei and one to Sarawak. Only Hoya kerangasensis is found in Brunei, Sabah and Sarawak, and only H. sangguensis is also found outside Borneo in Peninsular Malaysia. With these new species the number of Hoya of Borneo reaches 85 species and four subspecies. long, c. 1 mm diam., pinkish white, glabrous. Calyx lobes broadly triangular, c. 1.5 × 1 apex acute, outside, glabrous inside; basal colleters one at each calyx lobe sinus, oblong, c. 0.1 mm long. Flowers negatively geotropic. Corolla rotate with reflexed lobes, c. 1.5 cm diam. when flattened; tube 1–2 mm long, white inside, pinkish outside, glabrous; oblong, c. 7 × 4 mm, white inside, pinkish outside, glabrous. at the base of staminal c. 1 mm wide, glabrous. Climber, epiphytic, latex white. Stems of two types: climbing, with adventitious roots, internodes 5–12 cm long, sterile; non climbing, without adventitious roots, internodes 1.5–3 cm long, fertile, both types cylindrical, stout to slender, 1.5–5 mm diam., pubescent turning glabrescent when mature. Leaves: petiole terete, channelled above, 4–8 mm long, 1.2–2 mm diam., pubescent; lamina elliptic, very thick and coriaceous, 2.5–6.5 × 1–2.5 cm, dark green, glabrous above, very sparsely pubescent below, margin recurved, sparsely ciliate, apex rounded, base attenuate to acute; venation pinnate, secondary veins indistinct; basal colleters not observed on the available material. Inflorescence one per node, pseudo-umbelliform, convex, consisting of 9–20 flowers; peduncle extra-axillary, tropism unknown, likely positive, terete, 0.5–1.5 cm long, 1–1.5 mm diam., older peduncles forming a rachis from previous flowerings, pubescent; pedicels filiform, 23–28 mm long, c. 0.5 mm diam., glabrous. Calyx 2.5–3 mm diam., calyx lobes oblong, 0.8–1.1 × 0.4–0.5 mm, apex rounded or acute, dull red, outside sparsely pubescent, inside glabrous, ciliate; basal colleters one at each calyx lobe sinus, ovate, c. 0.1 mm long. Corolla rotate with reflexed lobes, 6–8 mm diam. when flattened, dark crimson; tube 1–1.2 mm long, outside glabrous, inside densely pubescent, glabrescent towards the centre; lobes ovate, 3–4 × 1.8–2.2 mm, apex acute, outside glabrous, inside densely pubescent. Gynostegium sub-sessile. Corona one per node, convex, consisting of 6–10 flowers; peduncle negatively geotropic or laterally held, 2–10 cm long, 1.2– 1.6 mm diam., glabrous; pedicels c. 20 × 1 mm, pubescent. Calyx lobes deltate, c. 2 × 1 mm, apex acute, pubescent outside, glabrous inside; basal colleters one at each calyx lobe sinus, oblong, c. 0.1 mm long. Flowers negatively geotropic. Corolla reflexed, c. 1.5 cm diam. when flattened; tube 2–3 mm long, inside pale yellow to red, basally pubescent, outside very pale yellow to pale pink, glabrous; lobes triangular, c. 7 × 4 mm, apex acute, yellow with orange tips, yellowish red or red, margin slightly recurved. Gynostegium sessile. Corona staminal, 3.5–4 mm high, c. 5 mm diam., white with pink centre or fully red; lobes erect, broadly ovate, 3.5–4 × 2.5–3 mm, inner process a c. 0.5 mm long acute upcurved tip, outer process apex rounded, with basal revolute margins. Anthers ovate, with apical round membranous appendage c. 0.7 × 0.7 mm. Pollinia oblong, 900–1000 × 300–400 µm with a thin pellucid margin, corpusculum dark brown, guitar-shaped, 250–300 × c. 200 µm, caudicles attached to the base of the corpusculum, c. 100 µm long. Ovary oblongoid, c. 1.5 × 0.5 mm, glabrous. Fruit and seed not observed. cream, very finely pubescent to glabrescent, outside white to very pale pink, shiny and sparsely pubescent, margin recurved, apex acuminate. Gynostegium sessile. Corona staminal, c. 3 mm high, 6.5–8 mm diam., cream; lobes ovate, 2.5–3 mm × c. 1.5 mm, inner process oblong, shortly upcurved reaching just below the style head, apex acute, pinkish, outer process slightly raised, apex rounded. Anthers ovate, with apical round membranous appendage c. 1 × 1.2 mm. Pollinia oblong, 680–720 × 250–300 µm, with round apex and base and evident pellucid margin, corpusculum oblongoid, 400–500 × 280–320 µm, caudicles triangular, attached to the mid-section of the corpusculum, c. 120 µm long. Ovary conical, 1.5–2 mm long, c. 0.7 mm wide at the base, pubescent, apex round. Fruit and seed not observed.